The present invention generally relates to doors and particularly to bifold, overhead doors.
In prior overhead doors, the upper and lower door panels if held in a parallel, horizontal open position have a tendency to fall into the doorway about the hinges of the upper door panel. One method to overcome this tendency was to angle the lower door panel from the doorway to the upper door panel to form a triangular support for the door, rather than bringing the lower door panel to a horizontal position. However, this greatly increased the height of the door and/or decreased the overhead room of the door in its open position. Prior attempts to provide support for overhead doors in their open positions also included cantilever beams extending from the building, spring systems, and the like which are of complicated construction, are impractical for large overhead doors, and/or are otherwise disadvantageous. Prior art examples of such door support systems are disclosed in U.S. Pat. Nos. 2,573,181 and 3,504,729 to J. H. Burr and J. A. Alton, respectively.
Thus, a need has arisen for an overhead door including a simple support system for the door panels in their open position which overcomes the disadvantages of prior overhead doors.